Unless `-s` or `--submodule` is specified, and as long as each
test is run in its own place or process, require a `configure-runtime`
submodule of the specified module before running the module or its
`test` submodule.
For example, this change makes `raco test` run `htdp/bsl` tests
with printing configured correctly for `htdp/bsl`.
Fix the decision about whether "mzlib" will be found by only
setting the collection path in an executable. The old test
made sense only with the pre-repo-split organization.
